They need to be a snug fit around the angular bushings to help keep the mud and dust out of them. 14.5mm might be a little looser fit by enough to let water in.

The 20mm x 1.5mm O-ring will also be squeezed a bit tighter than the factory 1.25mm thick O-ring between the suspension pieces so it may end up getting bunched up and shearing sooner if it's this hard a rubber.

I have been pretty happy with my 950, but I agree with a previous post...I am getting tired of the hurdles to keep it running. I have learned how to perform all service to the frame, but it's kinda hard to keep it creak-free (not to mention little things like the o-rings). I'm married to this frame for another 4-5 years, but I may be looking elsewhere when it comes time to replace it.